Compasses for describing ellipses.



G. B. GIRIGLIANO. GOMPASSES FOR DESCRIBING ELLIPSBS.

APPLICATION FILED APR. 23, 1912.

Patented Feb. 16, 1915.

'2 SHEBTSSHEET 1.

G. B.,GIRIGLIANO. GOMPASSES FOR DESCRIBING BLLIPSES.

APPLICATION FILED APR. 23, 1912.

Patented Feb. 16, 1915.

"2 SH FITS-SHEET 2.

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Ta all whom. it may concern Be it known that I, GIOVANNI BA'I'IISTACmIoLIANo, a subject of the King of Italy, residing at Turin, Italy,have invented certain new and useful Im rovements in Gompasses forDescribing llipses; and I do hereby declare the following to be a full,

clear, and exact description of the invention,

.against rotatlon, but allow oscillation in all such as will enableothers skilled in. the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and to lettersor figures of reference marked thereon, which form a part of thisspecification.

The invention has 'for its object compasses which permittracing'ellipses and, eventually, circles. j

The compasses, for the purpose of describing ellipses, differs from theusual compasses as follows: The centering leg of the compasses, duringthe tracing operation, is supported by a device serving to prevent therotation of the said leg, but allowing its. inclination in alldirections; whereas the leg whichv carries the pencil-point is jointedwith the centering leg'so as to be free of displacing itself in alldirections, and, during the tracing operation, it is guided by a templetof circular shape, which is securely connected with the centering leg.

A form of construction of the said compasses has been illustrated by wayof example in the accompanying drawing, in which Figures 1 and 2 show inside elevation and in front elevation, respectively, the compasses readyto use. Fig. 3 is a section along line 3-3 of Fig. 1 and shows a plan ofthe 1 whole guiding plate or circular templet;

Fig. 4 is a similar view to'Fig. 3, but with the parts in differentrelative position; Fig. 5 shows a cross section of e said templet on theline 5"'5" of Fig. 3; Fig. 6 shows some curves traced with the saidcompasses. The compasses according to the present invention, consist of.the leg 1, referably of square section, and whose en is provlded wlththe centering point 2; and the leg 3, also preferably of square section,slightly concave on its inward side 3' (Fig. 1), and whose upper end isjointed to the upper end of the leg 1 so as to be movable in alldirections. This joint is preferably constructed as a ball and socketjoint, consisting of the ball 4 forming the upper end of'the leg 1,

' Specification Letters Patent.

, 1 Application filed April 28, 1912. Serial No. 692,580.

Patented Feb} 16, 1915.

and of the spherical socket 5 composed of two pieces connected togetherand to the up-' erably united in a single piece invertibly mountedaround a pivot with screw 8.

In order to secure the centering leg directions, I preferably provide acentering frame or bridge shown in longitudinal section in vFig. 1. Thecentering frame or bridge consists of the central-body 9, provided withtwo points 10, 10 at its sidesand with the central point 11 projectingfrom the bottom of the body 9; the said point 11 being disposed on thesame straight line passing through the two points 10, 10 and equallydistant from each of them. The upper are 12 of the said centering frameor bridge, is provided with an oblong slot 12 through which isintroducedthe leg 1,

whose centering point 2 adjusts itself on the bottom of a central cup 9of the body 9.

It is obvioiis, that'the said centering frame, which, when it is securedby means of its three points 10, 10, 11 on the drawing, is preventedfrom rotation, and that it as a consequence prevents any rotation of theleg 1 because this leg is of square section and of the same width as theslot 12? of the are 12. The said leg 1 is nevertheless free to oscillatein all directions, that is to say: in longitudinal direction along theslot 12, and in transverse direction by causing at the same time theoscillation of the centerin frame. a

lhe guiding device, .whose scope is that of leg 3 the desiredelliptical'course consists essentially of a circular templet 13, made ofmetallic plate, which, by means of its base 14, is mounted capable ofsliding longitudinally on the supporting plate 15 (Figs. 1 and 3 to 5).This supporting plate 15, by means insuring to the tracing point 6v or 7of'the of its central projections 15 bent at right angles, and by meansof the screws 16, 16, is mounted tothe sliding block 17 so as to becapable of oscillating. This block is slidably mounted along the le landprovided with a pressure screw 18 or securing it in the desired positionalong the leg 1. The longitudinal sliding of the templet 1 and of itsbase 14 in' regard to the sup ing plate 15, is obtained. by means of theslots 15" formed in the same plate 15 and through which slots pass thescrews 19, 19 threaded in the base 14. The control of the longitudinaldisplacement of the said' templet is obtained by means ofthe screw 20threaded in the rear projection 21 of the plate 15, the end of the saidscrew engaging the cross piece 14 of the base 14 so as to be capable ofrotation. It is obvious, that, when the screw 20 is rotated in one or inthe other direction, the templet is caused to dis- 'place itselflongitudinally in one or the other direction in regard to its centeredposition shown in Fig. 3. Thus, for instance, in Fig. 4 the templet hasbeen shown as if it were entirely displaced toward the front.

The oscillation movement of the Whole guiding device around the screws16 of the stood how the said compasses can be used and operated.Firstly, the centering frame is mounted in its right place on thedrawing, so that its central point 11 issituated on the center 11' ofthe ellipse to be traced (Fig. 6), and so that the two side points 10,

10 are fixed in two pointslO, 10 of the smaller axis 24 of the ellipse.The end of the leg 1 is now inserted through the slot 12 of the centerinframe, and the centering point 2 place in the central cup 9. Then theleg 3 is swung around the templet 13, while maintaining the concaveinward side 3 of the leg 3 in contact with the edge of the plate 13, andthe tracing point of the leg 3 (pencil point 6, or pen point 7 incontact with the drawing, which is possible in consequence of the factthat the centering leg 1 is free to be inclined in all directions.

In'this manner it is possible to describe the I half ellipse 25; thetracing of the other half 25 is obtained in an identical manner byretracting momentarily the leg 1 from the centering frame and by turningthe whole instrument 180.

It is obvious that the length of the axes of the described ellipse, aswell as the proportion between the said axes, depend respectively on theheight in which the templet is placed along the leg 1, and on theincllnation of the said templet in respect to the leg 1. In fact, if thetracing of the ellipse 25, 25 (Fig. 6) has been carried out with thetemplet disposed in the position indictated in Fig. 1, and if it thenshould be desired to describe a larger or asmaller ellipse (as indicatedby 28 28'), it would be suficient to respectively raise or lower thetemplet 13'along the leg 1. If on the other maaaee would then suflice toincline the templet 13 -as shown in dotted lines in Fig. '1.

From the foregoing it will be understbod,

that with the possibility of regulating the height and the angularposition of the templet 13 in regard to the leg 1, it would be possibleto describe an ellipse having axes of a given length.

It is to be noted here, that, in order to describe arcs of ellipses withexactness, it is necessary, that, corresponding to the height of thetemplet 13 along the leg 1, the position of the said templet be adjustedin longitudinal directionfwhich is attained by operating the screw 20.In fact, if the templet 13 were always maintained centered, as in Fig.3, without regard to its height along the leg 1, there'would be obtained(Fig. 6)

not perpendicular to the said axis. Where.

as, by means of suitable displacement from the central position of thetemplet 13 in one direction oranother, as required by operating thescrew 20 in one direction or another, it will now be possible to obtaintracings of real elliptical arcs 25 and 28. The adjustment inlongitudinal direction by means of the screw 20 of the templet 13 doesnot present an difficulty, and is accomplished very rapi 1y by theoperator before he begins tracing the ellipse. In order to insureexactness of the said adjustment the following artifice may be resortedto, taking advantage of the fact that the legs' 1 and 3 have a squarecross section.

After having fixed the centering frame of one of the parallel side facesof the leg 3 is caused to place itself in the same plane as thecorresponding side face of the leg'l. In order to be sure that thiscondition is satisfied, a straight edge is leaned simultaneously againstthe side faces of the legs 1 and 3.

The compasses described above may also be used for tracing circles, byscrewing in the thumb screw 29 threaded in the spherical socket 5, untilits point enters the meridian slot 4 formed in the sphere 4. The leg 3has then only the opportunity of being oscillated in one'plane, and thecompasses can now be used as if they were ordinary compasses, aftertheguiding-device or templet 13 and also the centering frame have beenremoved.

It is obvious that the invention vis not strictly limited to theparticular arrangements shown and described,' and' "that anymodifications within the range of every expert may be made as requiredor rendered advantageous by the circumstances or the requirements ofpractice without departing from the essential nature of the invention.

Claims.

1. A pair of compasses for tracing elliptical curves, having a centeringleg, a tracing leg, and a joint between the two legs permitting movementin all directions; means for locking said centering leg against rota- Ition, said, means permitting oscillation of said centering leg in oneplane only relative to said means, a templet mounted to slide in thelength direction on said centering leg and displaceable transverselythereof; said tracing leg being constructed to impinge. against the edgeof said templet.

2. A pair of compasses for tracing ellipe tical curves, having acentering leg,"a t:ac-

ing leg, and a joint between the two legs permitting movement in alldirections;"- means for locking said centering leg against I rotation,said means permitting oscillation v of said centering leg in one planeonly relative to said-means, a templet mounted to slide in the lengthdirection on said center-- ing leg and displaceable transversely thereofin said tracing le constructed to impinge against the edge 0 saidtemplet; said means comprising a shoe havin three downwardly projectingpoints all in a inement, a recess in said shoe provided with parallelwalls and corresponding flat surfaces on said centering leg constructedto impinge'against said parallel walls, a centering point at the lowerend of said centering leg, and a central pocket therefor 'in said shoe.7 3. A pair of compasses for tracing elliptical curves, having acentering leg, atracing leg, and a joint between the two legs permittingmovements in all directions, means for locking said centering leg aainst rotation, said means permitting'oscil ation. of said centering legin one plane only relative to said means, a circular templet havingsliding connection longitudinall and transversely relative to sa1dcentering leg and constructed to beoscillated in the longitudi- .-naldirection and to contact with said tracingleg.

/ 4. A pair of compasses for tracing elliptical curves, having acentering leg, a tracing leg, and a joint between the two legspermitting movement in all directions; means for locking said centeringleg against rotation, said means permitting oscillation of saidcentering leg in one plane only relative to said means, a circulartemplet constructed to contact with the inner side of said tracing le acarrier for said tem let transverse a 0 I n o guldes on sa1d carrier anda dlsplacing' screw. on said carrier and connected with saidtemplet forthe purpose of sliding the templet in a transverse plane relative tosaid carrier, and means for holding said carrier with the templet inadjusted position centering leg.

5, A pair of compasses for tracing elliptical curves, having a centeringleg, a tracing leg, and a joint between the two legs permitting movementin all directions; means for locking said centering leg against rota-.tion, said means permitting oscillation of said centering leg in oneplane only relative to said means, a circular templet constructed tocontact with the inner side of said tracing leg, a carrier for saidtemplet, transverse guides on said carrier and a displacing.s crew onsaid carrier and connected with said-templet for the purpose of slidingthe templet-in a transverse plane relative to said carrier, a slidemounted'around said centering leg and adapted to be longitudinallydisonsaid placed: thereon; said carrier being mounted to oscillate onsaid slide, a set screw for loci:- ing said slide in any desiredposition on sa1d centermgleg, and another set screw on said j 4 carrierto ,lock said carrier in any desired angular osition to said slide.

' oregoin specification signed at The Turin (Italy) this 9th day ofApril, 1912.

GIOVANNI BATTISTA CIRIGLIANO- Witnesses; v

JocnLYN Sonnamn, RAmioLmosI.

